This invention is directed to fluid-type rotating machines, and is more particularly concerned with vane-type pneumatic and hydraulic motors.
Conventional pneumatic motors have a cylindrical rotor that rotates on an axis that is eccentric to the axis of a cylindrical chamber with vanes that contact against the wall of the chamber. High pressure air is directed into the core of the rotor, and the force of air pressure, together with centrifugal force urges the vane outward against the chamber wall. Wear of the vanes results from this outward force and from the surface contact velocity. The rate of vane wear is further increased due to limited contact surface of the vane with the cylindrical chamber wall. That is, because of the eccentric disposition of the rotor with respect to the cylindrical chamber, the rotor vane tips to not seat squarely against the chamber wall. As the vane travels from the near or compression side towards the far or expansion side, only the trailing edge of the vane is in contact. The zone of contact moves forward at full extension, and then only the leading edge of the vane is in contact as it travels back to the compression side. Conventionally, wear is controlled by limiting the speed of the motor, and by injection of a liquid lubricant into the drive air.
Also, conventional vane motors require side porting, i.e., porting through the cylindrical wall, which must deal with the problem of repressurization. This means that conventional vane motors either require extensive internal machined porting, or else use a housing around the cylinder which has cast and machined porting. It would be desirable to reduce the complexity of the parting, and also reduce manufacturing costs, but this goal has eluded vane motor designers.
A number of rotary pumps and motors have been proposed with modified vanes and chambers, but to date no one has combined whatever teachings there may be in these designs to produce a more durable, lower cost pneumatic or hydraulic rotary motor. A revolving sleeve rotary vane pump with pivoted vanes is shown in U.S. Pat. No. 2,841,090. A rotary motor with pivoting vanes and a floating piston in the chamber is described in U.S. Pat. No. 2,585,354. A rotary pump with pivoted vanes is described in U.S. Pat. No. 2,011,451. However, nothing in these previous designs suggests a simple design for a durable and reliable air motor or fluid driven motor.